Page 158 - MATHEMATICS COURSE FOR SECONDARY SCHOOLS BOOK 2

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map to calculate it
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and doors?
Given the map of a country, how would you
fiGndivtehneashmoarpteostf daicstoaunncteryb,eytwoueecnantwuoseciaties?
ruler to measure the direct distance between
(ii) How accurate were the angles you
(b) Using only a ruler and compasses, have constructed?
7and the angle you drew in part (a), (d)coEnxsptlrauincthaonwgleysoouf:would construct
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and
(c)
angle that you have constructed.
compasses.
builders know the length of a wall, the true distance, though. To find the actual
les,
usin
the two cities. This does not give you the
(i) Use a protractor to measure each (i) 135° (ii) 157.5°
width of a room, how many rooms are to be distance, you must use the given scale of the
M
(ii) How accurate were the angles you have constructed?
constructed or where to place the windows map to calculate it.
SCALE DRAWING
and doors?
Scale drawing
Similarly, the builder can use the scale on
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S: RATIO AND PROPORTION When a house is being built, how do the
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Please supply ork
show you the house plan if they have one. Please
382
supYpoluy may be able to view plans at your thicsountry’s Town and Country Planning artDweoprkartment, where they are kept.
Maps and plans are scale drawings representing a view as seen from above.
(d) Explain how you would construct
Given a map of a country, you can use a the plans to calculate the length of a wall
these angles, using only ruler and
ruler to measure the direct distance between and the width of a room. Ask your parents to
compasses.
the two cities. This does not give you the show you the house plan if they have one.
What is a scale drawing?
true distance, though. To find the actual dYisotaunmcea,yyboeu ambluestousveietwhepglaivnesnatscyaoleurof the mcaopuntotrcya’slcTuolwatne iatn. d Country Planning
(i) 135° (ii) 157.5°
Here is a picture of a horse.
Department, where they are kept. Similarly, the builder can use the scale on
Scale drawing
In the following box, there
the plans to calculate the length of a wall
are three more pictures of horses.
What is a s
Maps and plans are scale drawings
Here is a pi
In the following box, there
and the width of a room. Ask your parents to
representing a view as seen from above.
cale drawing?
cture of a horse.
this artw
are three more pictures of
Do any of these resemble the first horse?
horses.
Each of the three horses inPlethaseebsouxppislysimilar to the first horse, althougthhnisoatrthweorskame size.
The three in the box are scale drawings of the first horse. They are drawn to scale.
Scale drawings are not always smaller than the object being drawn. Microscopic animals and tiny objects can be drawn to scale, so that the scale drawings are larger than real size.
Maps and plans: scale drawings
You are familiar with maps. Maps are scale drawings of places such as continents, countries and towns.
Given the map of a country, how would you find the shortest distance between two cities?
When a house is being built, how do the builders know the length of a wall, the width of a room, how many rooms are to be constructed or where to place the windows and doors?
uct Given a map of a country, you can use a
nd ruler to measure the direct distance between 152
the two cities. This does not give you the true distance, though. To find the actual distance, you must use the given scale of the